1. Field of the Invention
The present invention relates to a vehicle seat movable in the longitudinal direction of the vehicle, and more specifically to a vehicle seat of a simplified base plate mounting structure.
2. Description of the Prior Art
In automotive vehicles, in particular in passenger cars, the vehicle seats are so constructed as to be movable in the longitudinal direction of the vehicle according to driver's body size to improve driver's comfortability. The vehicle seat of this type, in general, comprises a pair of lower rails arranged on a vehicle body floor at an interval in the vehicle transversal direction and a pair of upper rails slidably disposed on the lower rails, respectively. Further, a pair of base plates with a seat reclining device for adjusting an inclination angle of the seat back are fixed on the upper rails, respectively. Further, the vehicle seat comprises a lock mechanism for locking the seat at any desired position in cooperation with a seat position locating member disposed on the lower rail or the vehicle body floor at the middle portion of the upper rail or the base plate.
In the above-mentioned structure, each base plate is fixed to the upper rail at two front and rear positions with bolts or rivets. In this prior-art structure, however, when a large load is applied to the seat, since the base plate is not fixed at the middle portion of the base plate, there exists a problem in that the strength of the base plate is not sufficient and therefore the base plate tends to be deformed or moved inward relative to the upper rail. To overcome the above-mentioned problem, it is possible to increase the thickness of the base plate for providing higher rigidity and larger mounting strength. However, there arises another problem in that the weight and the cost of the material increase. Therefore, conventionally, the base plate is fixed to the upper rail with bolts or rivets at the front, middle and rear positions.
In the prior-art vehicle seat mounting structure, however, since the base plate is fixed to the upper rail at three (front, middle, and rear) different positions, there still exists another problem in that the number of mounting steps increases and therefore the mounting cost is high.